Liquid atomizer



June 20, 1967 K. LOUDIN ETAL 3,326,470

LIQUID ATOMIZER Filed April 27, 1965 3 Sheets-Sheet 1 INVENTORS Kyle L. Loudin Ralph H. Merr man 6 rge usar BY ATTORNEY K. L. LOUDIN ETAL 3,326,470

LIQUID ATOMIZER 3 Sheets-Sheet 2 B V A m 90E 9m 00 m ml. m fiuuul e 1 3.4 III: m3 fi E5: o

June 20, 1967 Filed April 27, 1965 June 20, 1967 K. 1.. LOUDIN ETAL LIQUID ATOMIZER 3 Sheets-Sheet 3 Filed April 27, 1965 United States Patent Ofitice ffif ilg 3,326,470 LIQUH) ATDMIZER Kyle L. Loudin, Atwater, Ralph H. Merryman, Alliance,

and George Musat, Canton, Ohio, assignors to The Bahcoclr & Wilcox Company, New York, N.Y., a corporation of New Jersey Filed Apr. 27, 1965, Ser. No. 451,293 8 Claims. (Cl. 239-404) This invention relates generally to liquid atomizers and more particularly to a plunger-type fuel oil atomizer characterized by its capability of producing excellent atomization over a wider load range than has heretofore been possible.

For many years it has been common practice to design liquid fuel atomizers with a whirl chamber of diminishing circular cross-section into which the liquid fuel is tangentially introduced for ultimate discharge through an axially arranged orifice. With a properly proportioned whirl chamber and adequate oil supply pressure, such atomizers have been found to produce a desirable hollow conical spray of finely divided fuel droplets, which pattern is particularly suited to effect good fuel and air mixing in the usual type of circular burner used in steam generators. However, as the load ranges over which steam generators are required to operate increased, the simple whirl chamber atomizers (the so-called straight mechanical type) were found to be inadequate in that they were not capable of effecting suitable atomization over a wide load range, the breakdown of atomization at low throughput rates obviously being due to the reduced inlet velocity to the whirl chamber at low liquid flow rates. The acceptable load range or turndown ratio of straight mechanical atomizers is known to be about 2 r 3 to l. A major advance in the mechanical atomization art was the returnfiow atomizer wherein a substantial quantity of the liquid fuel entering the whirl chamber i constantly withdrawn therefrom at reduced through-put rates. In this way, the tangential velocities in the whirl chamber are maintained at a higher level at low firing rates. Acceptable turn-down ratios of about 6 to 1 are commonly obtained with return-flow atomizers, the limiting factor being the inability to withdraw large quantities of liquid from the whirl chamber without seriously affecting the flow characteristics therein.

The plunger-type atomizer, as shown for example in US. Patent 3,091,283, represents another ignificant advance in the art. This type of atomizer is again generally classified as being of the straight mechanical type; however, as load is decreased, a plunger diminishes the volume of the cylindrical whirl chamber and simultaneously reduces the flow of fluid thereinto through entrance orifices spaced along the length of the whirl chamber. Thus as rate is reduced, the total liquid flow entrance area is reduced so that high tangential velocities can be maintained within the whirl chamber at reduced rates. It has been found, however, that even a plunger atomizer of the type shown in the aforementioned patent has a limited turn-down, the limitation apparently being imposed by the whirl chamber diameter. At the lower through-put rates, it appears that high energy losses, principally due to the large surface area of the cylindrical whirl chamber, are induced with resulting breakdown of the tangential action. Thus, in its application, a straight mechanical plunger-type atomizer of the type shown in the aforementioned patent is limited to a turn-down ratio of slightly above 10 to 1. Of course, as disclosed in that US. patent, atomization in the plunger-type atomizer can be enhanced by introducing a highly expansible auxiliary fiuid such as air or steam into the whirl chamber; however, the addition of the auxiliary fluid involves additional operation and control problems which make it undesirable for certain applications where simplicity and reliability are the primary considerations.

Marine boilers in particular are required to operate over extremely wide load ranges, and with the recent trend toward automation in these installations it is now desirable that the turn-down ratio on individual burners be increased so that it is not necessary to withdraw any of the burners from service during low load operation. Such a system calls for an atomizer having a turn-down ratio approaching 50 to 1.

It is therefore an object of the present invention to provide a liquid fuel atomizer particularly adapted for use in marine boiler installations and characterized by a turn-down ratio higher than has heretofore been possible with a straight-mechanical type atomizer, i.e. in the range of 50 to 1. It is a further object of the present invention that the inventive atomizer be so arranged as to be easily adapted for automatic operation.

These and other objects are attained in the present invention wherein a plunger-type liquid atomizer comprises a first cylindrical whirl chamber having a discharge orifice in its terminal end. An annular passageway, to which pressurized liquid fuel is supplied, surrounds the first whirl chamber, and first opening means are disposed continuously along substantially the entire length of the wall of the first whirl chamber for the introduction of liquid fuel from the annular passageway to the whirl chamber. The first opening means includes a plurality of equally sized circular openings arranged in a helical pattern around the inner wall and closely spaced to overlap each other in the direction of the axis of the first whirl chamber so as to form, in effect, a continuous opening extending along substantially the entire length of the cylindrical wall of the whirl chamber. A first plunger fits closely within the first whirl chamber and is axially movable therewithin for varying the whirl chamber volume and for simultaneously sequentially closing the openings to control the quantity of liquid fuel entering the first whirl chamber in the upper portion of the load range of the atomizer. A second cylindrical whirl chamber is formed within the first plunger, the second whirl chamber terminating at its distal end in a second discharge orifice opening into the first whirl chamber. Liquid fuel is supplied to the second whirl chamber from the the annular passageway through second opening means formed in the wall of the second whirl chamber, the second opening means being formed in the base of an annular recess cut into the outside of the first plunger. The second opening means includes a series of equally sized circular openings smaller than the openings of the first series and formed in a closely spaced helical pattern so as to overlap each other in the direction of the second whirl chamber axis. A second plunger fits closely within the second whirl chamber and is axially movable therewithin for varying the volume of the second whirl chamber and for sequentially closing the openings of the second series to control the quantity of liquid fuel entering the second whirl chamber in the lower portion of the atomizer load range. A plunger drive system is provided for axially and sequentially moving the first and second plungers and includes a non-rotating drive rod rigidly connected to one of the plungers, spring means urging the first and second plungers in opposite axial directions from each other, and means limiting relative axial movement between the first and second plungers.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a partial sectional view of the distal end of the fuel atomizer assembly of the present invention, the atomizer parts in this view being in the full load position;

FIG. 2 is a partial sectional view, to smaller scale than FIG. 1, of the rearward or inlet end of the atomizer assembly;

FIG. 3 is a partial sectional view taken along line 33 of FIG. 1;

FIG. 3A is a developed view, foreshortened in height, showing the drilling pattern for the inlet openings of the first or main whirl chamber;

FIG. 4 is a partial sectional view taken along line 4-4 of FIG. 1;

FIG. 4A is a developed view, foreshortened in height, showing the drilling pattern of the inlet openings of the second whirl chamber;

FIG. 5 is a partial sectional view taken along line 55 of FIG. 2;

FIG. 6 is a partial sectional view of the distal end of the atomizer, the atomizer parts in this view being in an intermediate load position;

FIG. 7 is a partial sectional view of the distal end of the atomizer, the atomizer parts in this view being in the shut-01f or zero load position;

FIG. 8 is a sectional view of an alternate embodiment of the atomizer assembly of the present invention wherein atomization is enhanced by use of an expansible fluid.

The atomizer assembly, as shown in FIGS. 1 through 5 of the drawings, includes an atomizer body 11 having formed therein a threaded inlet 12 to which a liquid fuel or oil supply line (not shown) may be suitably attached. The fluid inlet communicates with a cavity 13 formed in the body 11, which cavity opens at its forward end to the tubular atomizer barrel 14 which is threadably attached to the body 11. At the distal end of the atomizer assembly (see FIG. 1) an end cap 15 is threadably connected to the end of the barrel 14 to secure the plunger cage 16 in position in a groove machined in the forward end of the barrel 14.

A rearwardly extending portion 16A of the plunger cage 16 is formed with a machined cylindrical inner surface 16B defining a first or main whirl chamber 20, the forward or discharge end of which tapers inwardly and terminates in a first or main discharge orifice 21. The rearwardly extending portion 16A is drilled with a first series of tangential openings 17, the specific arrangement of which is best shown in FIGS. 1, 3 and 3A. The circular openings 17 are all of substantially equal size and are arranged in a helical pattern around the cylindrical wall of the main whirl chamber 20, the openings 17 being closely spaced so as to overlap each othcr in the direction of the axis of the whirl chamber 29. This series of openings 17 thus forms, in effect, a continuous opening extending along substantially the entire length of the cylindrical inner wall of the main whirl chamber 20. A first or main plunger 22 fits closely and is axially slidable within the cylindrical inner surface 16B of the main whirl chamber 20. The forward end of the main plunger 22 is formed with a tapered surface 22A, aranged to mate with the taper on the forward end of the whirl chamber 20, and terminates in a cylindrical surface 22B sized to fit closely within the main discharge orifice 21. Immediately rearwardly of the tapered surface 22A, the cylindrical outer surface of the main plunger 22 is grooved to form a recessed cylindrical outer surface 23, which surface is provided with a second series of tangential openings 24 (smaller than the openings 17), the specific arrangement of which is substantially similar to the arrangement of the openings 17 in the main whirl chamber 20, i.e. (see FIGS. 1, 4 and 4A), the openings 24 are arranged in a helical pattern and are closely spacedso as to overlap each other in the direction 4 of the axis of the second whirl chamber 25, thus forming, in effect, a continuous opening extending substantially the entire length of the inner cylindrical wall of the second Whirl chamber 25.

The main plunger 22 is formed with an axially extending cylindrical bore defining a second whirl chamber 25 having a tapered forward end terminating in a second discharge orifice 26 opening into the main whirl chamber 20. A second plunger 30, fitting closely and being axially slidable within the cylindrical bore of the second whirl chamber 25, is formed at its forwardmost end with a tapered surface arranged to mate with the tapered forward end of the second whirl chamber.

The second plunger 30 is rigidly connected to (or is formed as an integral pant of) a plunger drive rod 40 extending axially rearwardly through the barrel 14 and the atomizer body 11 for attachment to the plunger drive mechanism 50 to be described hereinafter. Since the drive rod 40 is of greater diameter than the second plunger 30, at the junction of these members an annular end surface 41 is formed in the drive rod 40. A compressed spring 42 is disposed between the end surface 41 and the rearward end of the main or first plunger 22 so as to continuously urge'the main plunger 22 and the second plunger 30 in opposite axial directions from each other. Relative axial movement between the first and second plungers 22 and 30 is limited by a pin 43 diametrically attached to and extending from opposite sides of the second plunger 30 and arranged to extend into a pair of diametrically oppositely disposed axially elongated slots 44 formed in the main plunger 22.

The operation of the plunger mechanism whereby atomization is effected over a wide load range will be discussed hereinafter; moreover, it should be recognized at this point in the description that the plunger drive rod 40 must be accurately manipulated in an axial direction in order to effectively control the associated plunger mechanism parts.

The plunger drive mechanism 50 (see 'FIGS. 2 and 5) is attached to the atomizer body -11 at its rearward end by a threaded connection between the body 11 and the forwardly extending sleeve portion 51A of the sleeve member 51. Leakage past the threaded connection is precluded by an O-ring seal 52A arranged on the outer surface of the sleeve portion 51A and a gasket 52B disposed between the body 11 and an outwardly extending flange portion 51B of the sleeve member 51. The sleeve portion 51A is formed with an internal bore of slightly greater diameter than the drive rod 40, and an O-ring seal 53A is provided there'between to prevent the leakage of oil from the cavity 13 rearwardly along the drive rod 40. A second O-ring seal 53B is provided for the same purpose between the drive rod 40 and the rearward portion of the sleeve member 51. A pair of oppositely disposed parallel guide bars 55 are attached to the rearward end of the sleeve member 51 by bolts 54 and extend rearwardly therefrom for connection by bolts 57 with the back plate 56. A manually adjustable knob 60 extends through an opening in the back plate 56 and is rotatably retained therein by a bearing ring 61 and a locking ring 62 engaged with the forward end of the knob 60. The knob 60 is formed with an axial threaded opening in which is received the threaded rearward portion 40A of the drive rod 40. An axially movable guide block 65 is fixedly attached to the drive rod 40 immediately forward of the threaded portion 40A and is formed with parallel outer sides arranged for sliding engagement with the inner surfaces of the guide bars 55. A dial micrometer 66 may be suitably attached to the guide block 65 so that the plunger 66A of the dial micrometer 66 engages with the flange 51B of the sleeve member 51.

From the above, it can be seen that the plunger drive rod 40 may be selectively moved axially by rotating the knob '60, and that rotation of the drive rod 40 is precluded by virtue of its rigid attachment to the rotatably restrained guide block 65 and the cooperating effect of guide bars 55. The feature of the present invention whereby the drive rod 40 is prevented from rotating alleviates the seal problems around the drive rod 40 and facilitates the mounting of the micrometer 66 as shown, so that the axial position of the drive rod 49 may be accurately monitored.

For purposes of the following description of the operation of the atomizer assembly disclosed herein, reference should be made to FIGS. 1, 6 and 7 which show the relative position of the plunger assembly parts at various burner load conditions. As is the usual situation, for purposes of this description it will be assumed that fuel oil is supplied by a suitable pump to the atomizer assembly at a substantially constant pressure and flows through the barrel 14 toward the distal end of the atomizer. Referring to FIG. 1 (full load condition), the oil enters the main whirl chamber tangentially through the openings 17 and is discharged through the main orifice 21. It can also be seen that the portion of the oil flowing through the rearwardmost openings -17 flows first into the groove formed in the main plunger 22, and then enters the second whirl chamber via openings 24 for subsequent discharge through the second orifice 26 into the main whirl chamber 20. At this point in the description, it should be recognized that in order to prevent rearward movement of the main plunger 22, the compressed spring 42 must exert sufiicient force in the forward direction to overcome the rearward force exerted on the forward face of the main plunger 22 due to the pressure of the oil in the main whirl chamber 20.

As the plunger drive rod is moved forwardly by means of the plunger drive mechanism 50, the main plunger advances within the cylindrical portion 16A of the plunger cage 16, thus sequentially closing the openings 17 and thereby reducing the quantity of oil entering the main Whirl chamber 20, the oil flow through the openings 17 being substantially directly proportional to the axial position of the main plunger 22. Moreover, it should be recognized that as the fuel flow into the main whirl chamber 20 is being reduced by the forward progress of the plunger 22, the volume of the whirl chamber 20 is also being proportionally reduced so that high velocities are advantageously maintained therein. Referring now to FIG. 6, as the drive rod moves forward, the front tapered surface 22A of the main plunger 22 seats against the mating tapered surface in the forward end of the main whirl chamber 20, thus closing oif all the openings 17 except those which admit oil into the groove formed about the main plunger 22. At this point in the load range all of the fuel that is being atomized is passing through the openings 24 into the second whirl chamber 25 and is being discharged from the atomizer directly through the second discharge orifice 26, which is now disposed substantially concentrically with respect to the main orifice 21. It should be recognized that the relatively small diameters of the second whirl chamber 25 and the second discharge orifice 26 effect higher oil velocities and therefore produce better atomization than would be produced if the same amount of oil were being passed through the larger main whirl chamber 20 and discharge orifice 21.

Once the main plunger 22 has seated (as shown in FIG. 6), any further forward movement of the drive rod 40 will overcome the force exerted by the spring 42 and will move the second plunger 30 forward Within the second whirl chamber 25, thus sequentially closing the openings 24 and thereby reducing the total oil flow entering the second whirl chamber 25. In this manner, the oil flow can be controlled and the volume of the second whirl chamber proportionally reduced until the zero flow or shut-off position (shown in FIG. 7) is reached, at which point the second plunger 30 seats against the tapered inner surface of the second whirl chamber 25.

In a practical application of the above-described atomizer, it has been found advantageous to regulate the oil flow over the top to of the load range with the main plunger, and to control flow in the lower 10 to 20% of the load range with the second plunger 30; however, depending on the particular installation, these values may be changed by varying the size and number of the openings 17 and 24. At whatever fiow rate this switch-over is designed to take place, it should be recognized that only the main plunger 22 effects flow control in the highest portion of the load range and that only the second plunger 30 efiects flow control in the lowest portion of the load range.

The invention as described above is intended for use primarily with fuel oil of the generally lower grades, e.g., No. 6 or Bunker C fuel; however, it should be recognized that the atomizer of the present invention can be adapted for use with any liquid fuel.

In instances where extremely high turn-down ratios, and/or exceedingly fine atomization are required, a fluid assist may be built into the atomizer described above. In FIG. 8 there is shown a fluid assist atomizer embodying substantially all of the features of the above-described mechanical atomizer. For purposes of identification, like parts in FIG. 8 are given reference numerals similar to those parts of the atomizer shown in FIGS. 1 through 5. In the embodiment of FIG. 8, the atomizer body 11A is constructed with an additional inlet connection 12A to which may be attached an atomizing fluid supply line (not shown). The atomizing fluid fiows to the chamber 13A and passes through the openings 18 and 19 into a longitudinally extending passageway 28 formed within the drive rod 40A and terminating in the discharge orifice 29 at the distal end of the second plunger 30A. Thus, a highly expansible fluid such as air or steam may be passed through the drive rod 40A and discharged into the second whirl chamber 25 to aid in the atomization of the fuel oil.

While in accordance with the provisions of the statutes there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

What is claimed is:

1. A liquid atomizer comprising means defining a first whirl chamber having a cylindrical inner wall and a re stricted discharge orifice, means for supplying liquid tangentially into said first whirl chamber including first opening means extending along the length of said inner wall, a first plunger closely fitting within said first whirl chamber and axially movable therewithin for varying the volume of said first whirl chamber and for closing said first opening means to control the quantity of liquid entering said first whirl chamber over the upper portion of the load range of the atomizer, said first plunger forming a second whirl chamber having a cylindrical inner wall and a restricted discharge orifice, means for supplying liquid tangent-ially into said second whirl chamber over the entire load range of the atomizer including second opening means extending along the length of the inner wall of said second whirl chamber and communicating liquid flow-wise with said first opening means over the entire load range of the atomizer, a second plunger closely fitting within said second whirl chamber and axially movable therewithin for varying the volume of second whirl chamber and for closing said second opening means to control the quantity of liquid entering said second whirl chamber, and plunger drive means axially and sequentially moving said first and second plungers and operable to maintain liquid flow communication of said second opening means with said first opening means over the entire load range of the atomizer.

2. A liquid atomizer comprising means defining a first whirl chamber having a cylindrical inner wall and a restricted discharge orifice, means for supplying liquid tangentially into said first whirl chamber including first opening means extending along the length of said inner wall, a first plunger closely fitting within said first whirl chamber and axially movable therewithin for varying the volume of said first whirl chamber and for closing said first opening means to control the quantity of liquid entering said first whirl chamber over the upper portion of the load 7 range of the atomizer, said first plunger forming a second whirl chamber having a cylindrical inner wall and a restricted discharge orifice, means for supplying liquid tangentially into said second Whirl chamber over the entire load range of the atomizer including second opening means extending along the length of the inner wall of said second whirl chamber and communicating liquid flow-wise with said first opening means over the entire load range of the atomizer, a second plunger closely fitting within said sec ond whirl chamber and axially movable therewithin for varying the volume of second whirl chamber and for closing said second opening means to control the quantity of liquid entering said second whirl chamber, and plunger drive means axially and sequentially moving said first and second plungers and operable to maintain liquid fiow communication of said second opening means with said first opening means over the entire load range of the atomizer, said drive means including a drive rod rigidly connected to one of said plungers, and means restraining said drive rod from rotation.

3. A liquid atomizer comprising means defining a first whirl chamber having a cylindrical inner wall and a restricted discharge orifice, means for supplying liquid tangentially into said first whirl chamber including first opening means extending continuously along substantially the entire length of said inner wall, a first plunger closely fitting within said first whirl chamber and axially movable therewithin for varying the volume of said first whirl chamber and for closing said first opening means to control the quantity of liquid entering said first whirl chamher over the upper portion of the load range of the atomizer, said first plunger forming a second whirl chamber having a cylindrical inner wall and a restricted discharge orifice, means for supplying liquid tangentially into said second whirl chamber including second opening means extending continuously along substantially the entire length of the inner Wall of said second whirl chamber and communicating liquid flow-wise with said first opening means over the entire load range of the atomizer, a second plunger closely fitting within said second whirl chamber and axially movable therewithin for varying the volume of said second whirl chamber and for closing said second opening means to control the quantity of liquid entering said second whirl chamber over the lower portion of the load range of the atomizer, and plunger drive means for axially moving said first and second plungers and operable to maintain liquid flow communication of said second opening means with said first opening means over the entire load range of the atomizer.

4. A liquid atomizer comprising means defining a first stricted discharge orifice, means for supplying liquid tangentially into said first whirl chamber including first open ing means extending continuously along substantially the entire length of said inner wall, a first plunger closely fitting within said first whirl chamber and axially movable therewithin for varying the volume of said first whirl chamber and for closing said first opening means to control the quantity of liquid entering said first whirl chamber over the upper portion of the load range of the atomizer, said first plunger forming a second whirl chamber having a cylindrical inner Wall and a restricted discharge orifice, means for supplying liquid tangentially into said second Whirl chamber including second opening means extending continuously along substantially the entire length of the inner Wall of said second whirl chamber and communicating liquid flow-wise with said first opening whirl chamber having a cylindrical inner wall and a remeans over the entire load range of the atomizer, a second plunger closely fitting within said second whirl cham ber and axially movable therewithin for varying the volume of said second whirl chamber and for closing said second opening means to control the quantity of liquid entering said second whirl chamber over the lower portion of the load range of the atomizer, and plunger drive means for axially and sequentially moving said first and second plungers and operable to maintain liquid flow communication of said second opening means with said first opening means over the entire load range of the atomizer, said drive means comprising a drive rod rigidly connected to one of said plungers, and spring means urging said first and second plungers in opposite axial directions from each other.

5. A liquid atomizer comprising means defining a first whirl chamber having a cylindrical inner wall and a restricted discharge orifice, means for supplying liquid tangentially into said first whirl chamber including first opening means extending continuously along substantially the entire length of said inner wall, said first opening means including a plurality of circular openings arranged in a helical pattern about said inner wall and being closely spaced so as to overlap each other in the direction of the axis of the first Whirl chamber so as to form in effect a continuous opening extending substantially the entire length of said whirl chamber, a first plunger closely fitting within said first Whirl chamber and axially movable therewithin for varying the volume of said first Whirl chamber and for closing said first opening means to control the quantity of liquid entering said first whirl chamber over the upper portion of the load range of theatomizer, said first plunger forming a second whirl chamber having a cylindrical inner wall and a restricted discharge orifice, means for supplying liquid tangentially into said second whirl chamber including second opening means extending continuously along substantially the entire length of the inner wall ofsaid second whirl chamber and communicating liquid flow-wise with said first opening means over the entire load range of the atomizer, a second plunger closely fitting within said second whirl chamber and axially movable therewithin for varying the volume of said second whirl chamber and for closing said second opening means to control the quantity of liquid entering said second whirl chamber over the lower portion of the load range of the atomizer, a plunger drive means for axially-and sequentially moving said first and second plungers and operable to maintain liquid flow communication of said second opening means with said first opening means over the en-' tire load range of the atomizer.

6. A liquid atomizer comprising means defining a first whirl chamber having a cylidrical inner wall and a re-. stricted discharge orifice, means for supplying liquid tangentially into said first whirl chamber including first opening means extending continuously along substantially the entire length of said inner wall, a first plunger closely fitting within said first whirl chamber and axially movable -therewithin for varying the volume of said first whirl chamber and for closing said first opening means to control the quantity of liquid entering said first whirl chamber over the upper portion of the load range of the atom: izer, said first plunger forming a second whirl chamber having a cylindrical inner wall and a restricted discharge orifice, means for supplying liquid tangentially into said second whirl chamber including second opening means extending continuously along substantially the entire length of the inner wall of said second whirl chamber and communicating liquid flow-wise with said first opening means over the entire load range of the atomizer, a second plunger closely fitting within said second whirl chamber and axially movable therewithin for varying the vol ume of said second whirl chamber and for closing said second opening means to control the quantity of liquid entering said second whirl chamber over the lower portion of the load range of the atomizer, means forming a passage through said second plunger, means for introducing an expandible fluid through said passage into said second whirl chamber to assist atomization of the liquid, and plunger drive means for axially and sequentially moving said first and second plungers and operable to maintain liquid flow communication of said second opening means with said first opening means over the entire load range of the atomizer, said drive means comprising a drive rod rigidly connected to one of said plungers, means restraining said drive rod from rotation, spring means urging said first and second plungers in opposite axial directions from each other, and means limiting relative axial movement between said first and second plungers said drive rod restraining means including a pair of oppositely disposed parallel guide bars, and a guide block connected to said drive rod and arranged for sliding engagement with the inner surfaces of the guide bars.

7. A liquid fuel atomizer comprising means defining a first whirl chamber having a cylindrical inner wall and a tapered discharge end terminating in a first restricted discharge orifice, means for supplying liquid fuel tangen tially into said first whirl chamber including means enclosing an annular passageway surrounding said first whirl chamber, means for supplying pressurized liquid fuel to said annular passageway, and first opening means disposed continuously along substantially the entire length of said cylindrical inner wall, said first opening means including a first series of equally sized circular openings arranged in a helical pattern about said inner Wall and being closely spaced so as to overlap each other in the direction of the axis of said first whirl chamber, so as to form in eiiect a continuous opening extending substantially the entire length of said inner wall, a first plunger closely fitting within said first Whirl chamber and axially movable therewithin for varying the volume of said first whirl chamber and for sequentially closing the openings of said first series to control the quantity of liquid fuel entering said first whirl chamber in the upper portion of the load range of the atomizer, said first plunger having a tapered end portion arranged to mate with the tapered discharge end of said first Whirl chamber, said first plunger forming a second cylindrical whirl chamber having a cylindrical inner wall and a tapered discharge end terminating in a second restricted discharge orifice, means for supplying liquid fuel from said annular passageway into said second whirl chamber including means forming an annular recess about the outside of said first plunger, and a second series of equally sized circular openings smaller than the openings of said first series and formed within said annular recess in a helical pattern and being closely spaced so as to overlap each other in the direction of the axis of said second whirl chamber so as to form in effect a continuous opening extending substantially the entire length of the inner wall of said second Whirl chamber and communicating liquid flow-wise with said first opening means over the entire load range of the atomizer, a second plunger closely fitting within said second whirl chamber and axially movable therewithin for varying the volume of said second whirl chamber and for sequentially closing the openings of said second series to control the quantity of liquid fuel entering said second whirl chamber in the lower portion of the load range of the atomizer, said second plunger having a tapered end portion arranged to mate With the tapered discharge end of said second whirl chamber, and plunger drive means for axially and sequentially moving said first and second plungers and operable to maintain liquid flow communication of said second opening means with said first opening means over the entire load range of the atomizer.

8. A liquid fuel atomizer comprising means defining a first whirl chamber having a cylindrical inner wall and a tapered discharge end terminating in a first restricted discharge orifice, means for supplying liquid fuel tangentially into said first whirl chamber including means enclosing an annular passageway surrounding said first whirl chamber, means for supplying pressurized liquid fuel to said annular passageway, and first opening means disposed continuously along substantially the entire length of said cylindrical inner wall, said first opening means including a first series of equally sized circular openings arranged in a helical pattern about said inner wall and being closely spaced so as to overlap each other in the direction of theaxis of said first whirl chamber so as to form in efiect a continuous opening extending substantially the entire length of said inner wall, a first plunger closely fitting within said first whirl chamber and axially movable therewithin for varying the volume of said first whirl chamber and for sequentially closing the openings of said first series to control the quantity of liquid fuel entering said first whirl chamber in the upper portion of the load range of the atomizer, said first plunger having a tapered end portion arranged to mate with the tapered discharge end of said first whirl chamber, said first plunger forming a second cylindrical Whirl chamber having a cylindrical inner Wall and a tapered discharge end terminating in a second restricted discharge orifice, means for supplying liquid fuel from said annular passageway into said second whirl chamber including means forming an annular recess about the outside of said first plunger, and a second series of equally sized circular openings formed within said annular recess in a helical pattern and being closely spaced so as to overlap each other in the direction of the axis of said second whirl chamber so as to form in eifect a continuous opening extending substantially the entire length of the inner wall of said second whirl chamber and communicat ing liquid flow-Wise With said first opening means over the entire load range of the atomizer, a second plunger closely fitting within said second whirl chamber and axially movable therewithin for varying the volume of said second whirl chamber and for sequentially closing the openings of said second series to control the quantity of liquid fuel entering said second whirl chamber in the lower portion of the load range of the atomizer, said second plunger having a tapered end portion arranged to mate with the tapered discharge end of said second whirl chamber, means forming a passage through said second plunger, means for introducing an expandible fluid through said passage into said second whirl chamber to assist atomization of the liquid fuel, and plunger drive means for axially and sequentially moving said first and second plungers and operable to maintain liquid flow communication of said second opening means with said first opening means over the entire load range of the atomizer, said drive means comprising a drive rod rigidly connected to one of said plungers, means restraining said drive rod from rotation, spring means urging said first and second plungers in op posite axial directions from each other, and means limiting relative axial movement between said first and second plungers.

References Cited UNITED STATES PATENTS 1,051,908 2/1913 Normand 239-466 1,102,352 7/1914 Peabody et a1 239482 2,015,611 9/1935 Wettstein 239-466 2,558,779 7/1951 Pesce 239-477 2,624,624 1/ 1953 Kirschbaum 239-403 3,091,283 5/1963 Kidwell 239492 FOREIGN PATENTS 234,256 11/ 1963 Austria.

1,167,099 7/1958 France.

EVERETT W. KIRBY, Primary Examiner. 

1. A LIQUID ATOMIZER COMPRISING MEANS DEFINING A FIRST WHIRL CHAMBER HAVING A CYLINDRICAL INNER WALL AND A RESTRICTED DISCHARGE ORIFICE, MEANS FOR SUPPLYING LIQUID TANGENTIALLY INTO SAID FIRST WHIRL CHAMBER INCLUDING FIRST OPENING MEANS EXTENDING ALONG THE LENGTH OF SAID INNER WALL, A FIRST PLUNGER CLOSELY FITTING WITHIN SAID FIRST WHIRL CHAMBER AND AXIALLY MOVABLE THEREWITHIN FOR VARYING THE VOLUME OF SAID FIRST WHIRL CHAMBER AND FOR CLOSING SAID FIRST OPENING MEANS TO CONTROL THE QUANTITY OF LIQUID ENTERING SAID FIRST WHIRL CHAMBER OVER THE UPPER PORTION OF THE LOAD RANGE OF THE ATOMIZER, SAID FIRST PLUNGER FORMING A SECOND WHIRL CHAMBR HAVING A CYLINDRICAL INNER WALL AND A RESTRICTED DISCHARGE ORIFICE, MEANS FOR SUPPLYING LIQUID TANGENTIALLY INTO SAID SECOND WHIRL CHAMBER OVER THE ENTIRE LOAD RANGE OF THE ATOMIZER INCLUDING SECOND OPENING MEANS EXTENDING ALONG THE LENGTH OF THE INNER WALL OF SAID SECOND WHIRL CHAMBER AND COMMUNICATING LIQUID FLOW-WISE WITH SAID FIRST OPENING MEANS OVER THE ENTIRE LOAD RANGE OF THE ATOMIZER, A SECOND PLUNGER CLOSELY FITTING WITHIN SAID SECOND WHIRL CHAMBER AND AXIALLY MOVABLE THEREWITHIN FOR VARYING THE VOLUME OF SECOND WHIRL CHAMBER AND FOR CLOSING SAID SECOND OPENING MEANS TO CONTROL THE QUANTITY OF LIQUID ENTERING SAID SECOND WHIRL CHAMBER, AND PLUNGER DRIVE MEANS AXIALLY AND SEQUENTIALLY MOVING SAID FIRST AND SECOND PLUNGERS AND OPERABLE TO MAINTAIN LIQUID FLOW COMMUNICATION OF SAID SECOND OPENING MEANS WITH SAID FIRST OPENING MEANS OVER THE ENTIRE LOAD RANGE OF THE ATOMIZER. 